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Ammonium formate aided catalytic transfer hydrogenation has been employed in the cleavage, and concommitant deprotection, of the pentapeptide leucine enkephalin from the Merrifield peptide resin under ambient conditions of temperature and pressure in a neutral medium. 相似文献
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Márcio AF Belo-Filho Franklina MB Toledo Bernardo Almada-Lobo 《The Journal of the Operational Research Society》2014,65(11):1735-1747
Setup operations are significant in some production environments. It is mandatory that their production plans consider some features, as setup state conservation across periods through setup carryover and crossover. The modelling of setup crossover allows more flexible decisions and is essential for problems with long setup times. This paper proposes two models for the capacitated lot-sizing problem with backlogging and setup carryover and crossover. The first is in line with other models from the literature, whereas the second considers a disaggregated setup variable, which tracks the starting and completion times of the setup operation. This innovative approach permits a more compact formulation. Computational results show that the proposed models have outperformed other state-of-the-art formulation. 相似文献
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Stability and convergence of the spectral Lagrange-Galerkin method for mixed periodic/non-periodic convection-dominated diffusion problems 总被引:1,自引:0,他引:1
We present a convergence analysis of the spectral Lagrange-Galerkinmethod for mixed periodic/non-periodic convection-diffusionproblems. The scheme is unconditionally stable, independentof the diffusion coefficient, even in the case when numericalquadrature is used. The theoretical predictions are illustratedby a series of numerical experiments. For the periodic case,our results present a significant improvement on those givenby Süli & Ware (1991) SIAM J. Numer.Anal.28, 423-445). 相似文献
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Daniele Del Giudice Emanuele Spatola Matteo Valentini Cecilia Bombelli Gianfranco Ercolani Stefano Di Stefano 《Chemical science》2021,12(21):7460
In this report it is shown that nitroacetic acid 1 (O2NCH2CO2H) can be conveniently used to control the pH of a water solution over time. Time-programmable sequences of the kind pH1(high)–pH2(low)–pH3(high) can be achieved, where both the extent of the initial pH jump (pH1(high)–pH2(low)) and the time required for the subsequent pH rising (pH2(low)–pH3(high)) can be predictably controlled by a judicious choice of the absolute and relative concentrations of the reagents (acid 1 and NaOH). Successive pH1(high)–pH2(low)–pH3(high) sequences can be obtained by subsequent additions of acid 1. As a proof of concept, the method is applied to control over time the pH-dependent host–guest interaction between alpha-cyclodextrin and p-aminobenzoic acid.Predictable and time-programmable sequences of the kind pH1(high)–pH2(low)–pH3(high) in water solution are obtained by a judicious choice of the concentration of nitroacetic acid undergoing decarboxylation. 相似文献
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Anne‐Marie Leduc Mark S. Mashuta Arno F. Spatola 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(4):487-488
The small synthetic peptide, benzyl 2‐(tert‐butoxycarbonyl‐amino)isobutyrate, C16H23NO4, has the α‐helical conformation [|?| = 55.8 (2)° and |ψ| = 37.9 (2)°] observed in peptide fragments of peptaibols containing the α‐aminoisobutyric acid (Aib) residue. The structure shows no intramolecular hydrogen bonding, which would disrupt the limited conformational freedom associated with this amino acid. Two weak intermolecular hydrogen contacts are observed. 相似文献